Battery monitoring apparatus

ABSTRACT

A battery monitoring apparatus includes a battery ECU, a plurality of voltage monitors, and a wireless device. The wireless device contains a main unit disposed to the battery ECU and sub units disposed to the corresponding voltage monitors. In response to establishment of communication connection of wireless communication between the main unit and the sub units, the main unit wirelessly transmits a command by the battery ECU to the sub units, and the sub units wirelessly transmit voltage information detected by the voltage monitors to the main unit. The wireless device acquires voltage monitor information prior to establishment of initial communication connection, and establishes communication connection based on the voltage monitor information. The battery ECU or each voltage monitor is provided with a storage unit configured to store voltage monitor information. At re-connection, the wireless device performs communication re-connection using the voltage monitor information stored in the storage unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. bypass application of InternationalApplication No. PCT/JP2020/010015 filed on Mar. 9, 2020 which designatedthe U.S. and claims priority to Japanese Patent Application No.2019-045836 filed on Mar. 13, 2019 and Japanese Patent Application No.2019-192981 filed on Oct. 23, 2019, the contents of all of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a battery monitoring apparatusconfigured to monitor a plurality of unit batteries provided to abattery pack mounted on a vehicle.

BACKGROUND

Some battery monitoring apparatuses include a battery ECU and aplurality of voltage monitors, and perform wireless communicationbetween the battery ECU and the voltage monitors. The voltage monitorsare disposed to corresponding battery blocks into which the plurality ofunit batteries is grouped. The battery ECU wirelessly transmits acommand to the voltage monitors. Each voltage monitor detects voltageinformation of the unit batteries and wirelessly transmits the detectedinformation to the battery ECU. An example in the literature of abattery monitoring apparatus configured to perform wirelesscommunication in this manner is JP 6093448 B.

SUMMARY

The battery monitoring apparatus according to the present disclosure isan apparatus configured to monitor a plurality of unit batteriesprovided to a battery pack mounted on a vehicle, and includes a batteryECU, voltage monitors, and a wireless device. The voltage monitors aredisposed to corresponding battery blocks into which a plurality of theunit batteries is grouped, to detect voltage information of the unitbatteries. The wireless device contains a main unit disposed to thebattery ECU and sub units disposed to the corresponding voltagemonitors. In response to establishment of communication connection ofwireless communication between the main unit and the sub units in thewireless device, the main unit wirelessly transmits a command by thebattery ECU to the sub units, and the sub units wirelessly transmit thevoltage information to the main unit.

The main unit receives wireless signals from the sub units prior toinitial establishment of the communication connection, such that thewireless device acquires voltage monitor information, which isinformation of the voltage monitors, and establishes the communicationconnection using the voltage monitor information.

At least one of the battery ECU and each voltage monitor is disposedwith a storage unit to store the voltage monitor information. At a timeof re-connection in which communication re-connection is reestablishedafter disconnection of the initial communication connection, thewireless device establishes the communication re-connection using thevoltage monitor information stored in the storage unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features of the present disclosure will be made clearer by thefollowing detailed description, given referring to the appendeddrawings. In the accompanying drawings:

FIG. 1 is a circuit diagram illustrating a battery monitoring apparatusaccording to a first embodiment;

FIG. 2 is a flowchart illustrating a processing flow at an initialoperation;

FIG. 3 is a flowchart illustrating a processing flow at a secondoperation or later;

FIG. 4 is a flowchart illustrating a processing flow when communicationconnection is disconnected during communication;

FIG. 5 is a flowchart illustrating a processing flow at a secondoperation or later in a second embodiment;

FIG. 6 is a circuit diagram illustrating a battery monitoring apparatusaccording to a third embodiment;

FIG. 7 is a flowchart illustrating a processing flow at an initialoperation;

FIG. 8 is a flowchart illustrating a processing flow at a secondoperation or later;

FIG. 9 is a schematic diagram illustrating a first communication modeand a second communication mode;

FIG. 10 is a flowchart illustrating a processing flow at a secondoperation or later in a fourth embodiment;

FIG. 11 is a flowchart illustrating a processing flow at an initialoperation in a fifth embodiment;

FIG. 12 is a flowchart illustrating a processing flow at a secondoperation or later; and

FIG. 13 is a schematic diagram illustrating a first communication modeand a second communication mode in a sixth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Usually, a battery monitoring apparatus needs to confirm that a batterypack is normal before departure of a vehicle. Therefore, communicationconnection between a battery ECU and voltage monitors needs to beestablished to detect voltages of unit batteries, before departure of avehicle. In this regard, a known wireless-type battery monitoringapparatus, such as disclosed in JP 6093448 B, activates a battery ECUand voltage monitors in response to a power switch of a vehicle beingturned ON, and starts connection processing for wireless communication.However, a time taken for the connection processing of wirelesscommunication is often longer than that for connection processing ofwired communication. This lengthens a time from when a power switch of avehicle is turned on by a driver to when the vehicle becomes ready tomove. As a result, comfort of a driver deteriorates.

In addition, if connection of wireless communication is unintentionallydisconnected while a power switch of a vehicle is ON, communicationre-connection also comes to take time, because connection of wirelesscommunication often takes time as described above.

The present disclosure has been made in view of the above-describedsituation, and has as its main object to provide a battery monitoringapparatus which can smoothly perform connection of wirelesscommunication.

The battery monitoring apparatus according to the present disclosure isan apparatus configured to monitor a plurality of unit batteriesprovided to a battery pack mounted on a vehicle, and includes a batteryECU, voltage monitors, and a wireless device. The voltage monitors aredisposed to corresponding battery blocks into which a plurality of theunit batteries is grouped, to detect voltage information of the unitbatteries. The wireless device contains a main unit disposed to thebattery ECU and sub units disposed to the corresponding voltagemonitors. In response to establishment of communication connection ofwireless communication between the main unit and the sub units in thewireless device, the main unit wirelessly transmits a command by thebattery ECU to the sub units, and the sub units wirelessly transmit thevoltage information to the main unit.

The main unit receives wireless signals from the sub units prior toinitial establishment of the communication connection, such that thewireless device acquires voltage monitor information, which isinformation of the voltage monitors, and establishes the communicationconnection using the voltage monitor information.

At least one of the battery ECU and each voltage monitor is disposedwith a storage unit to store the voltage monitor information. At a timeof re-connection in which communication re-connection is reestablishedafter disconnection of the initial communication connection, thewireless device establishes the communication re-connection using thevoltage monitor information stored in the storage unit.

According to the present disclosure, the following effects are obtained.Since the wireless device establishes communication connection usingvoltage monitor information, communication connection can beappropriately established depending on voltage monitor information.However, if it takes time to acquire voltage monitor information, ittakes time to establish communication connection.

In this regard, the present disclosure is configured that communicationre-connection is performed using voltage monitor information stored inthe storage unit at a time of re-connection, with the result thatalthough a time for acquiring voltage monitor information is necessaryat an initial communication connection, a time for acquiring voltagemonitor information is reduced at the subsequent re-connections.Accordingly, a second or later communication connection can be smoothlyreestablished.

Next, embodiments of the disclosure will be described with reference tothe drawings. However, the present disclosure is not limited to aspectsof the embodiments, which can be appropriately modified and carried outwithin a scope that does not depart from the purpose of the disclosure.

First Embodiment

FIG. 1 is a circuit diagram illustrating a battery monitoring apparatus51 and its peripheries according to a first embodiment. A vehicleincludes a power switch 70, a battery pack 60, an auxiliary battery 67,and a battery monitoring apparatus 51, and is further provided withpower lines 31 and 38 and a detection line 39. The battery pack 60contains a plurality of unit batteries 63. The plurality of unitbatteries 63 is grouped into a plurality of battery blocks 62. Thebattery monitoring apparatus 51 includes a battery ECU 10 and aplurality of voltage monitors 20.

The battery ECU 10 contains a power source 11, an MCU 13, a main unit16, and a storage unit 17, and is further provided with a power port 10a, an electrical wire α, and a communication wire β. The MCU 13 has apower switch 13 a. The main unit 16 has a power switch 16 a and anantenna 16 b.

Each voltage monitor 20 includes a power source 21, a monitoring IC 23,a sub unit 26, and a storage unit 27, and is further provided with apower port 20 a, a plurality of detection ports 20 d, an electrical wireα, a communication wire β, and a detection wire δ. The monitoring IC 23has a power switch 23 a. The sub unit 26 has a power switch 26 a and anantenna 26 b.

Next, the above-described members and others will be described. Thepower switch 70 is an activation switch of a power unit for running avehicle. The power unit of a vehicle may be one or both (a hybrid) of anengine and a motor.

A plurality of battery blocks 62 is connected in series. Each batteryblock 62 is constituted by a plurality of unit batteries 63 connected inseries. Each unit battery 63 may be a single cell battery or a pluralityof cell batteries connected in series. Although the cell battery is alithium battery in the present embodiment, other batteries may be used.

The auxiliary battery 67 is connected to the power port 10 a of thebattery ECU 10 via a power line 31. The power source 11 is connected tothe power port 10 a, the MCU 13, the main unit 16, and the storage unit17 via the electrical wires a. The power source 11 supplies powersupplied from the auxiliary battery 67 to the MCU 13, the main unit 16,and the storage unit 17.

The power switch 13 a switches ON/OFF power supplied from the electricalwire α to the MCU 13. The power switch 16 a switches ON/OFF powersupplied from the electrical wire a to the main unit 16. In response tothe power switch 70 being turned ON, the power switches 13 a and 16 a ofthe MCU 13 and the main unit 16 are turned ON. Accordingly, the batteryECU 10 is activated. On the other hand, in response to the power switch70 being turned OFF, the power switches 13 a and 16 a of the MCU 13 andthe main unit 16 are thereafter turned OFF. Accordingly, the battery ECU10 is placed in a sleep mode. The sleep mode is a state in whichalthough activation of the MCU 13 and the main unit 16 are terminate,activation of the storage unit 17 is not terminated.

The MCU 13, for example, gives a command to the monitoring IC 23.Examples of such a command include a command to acquire voltageinformation of the unit batteries 63 and a command to discharge the unitbatteries 63. The main unit 16 contains a communication controller andan RF part. The MCU 13 and the main unit 16 are communicably connectedvia the communication wire β. The MCU 13 transmits to the main unit 16,for example, a command for the monitoring IC 23, via the communicationwire β. On the other hand, the main unit 16 transmits, for example,voltage information wirelessly received from the sub units 26, to theMCU 13 via the communication wire β. The storage unit 17 has a memory.

The battery pack 60 is connected to the power port 20 a of each voltagemonitor 20 via the power line 38. The power source 21 is connected tothe power port 20 a, the monitoring IC 23, the sub unit 26, and thestorage unit 27 via the electrical wires a. The power source 21 suppliespower supplied from the unit batteries 63, to the monitoring IC 23, thesub unit 26, and the storage unit 27.

The power switch 23 a switches ON/OFF power supplied from the electricalwire α to the monitoring IC 23. The power switch 26 a switches ON/OFFpower supplied from the electrical wire a to the sub unit 26. Inresponse to the power switch 70 being turned ON, the power switches 23 aand 26 a of the monitoring IC 23 and the sub unit 26 are turned ON.Accordingly, the voltage monitor 20 is activated. On the other hand, inresponse to the power switch 70 being turned OFF, the power switches 23a and 26 a of the monitoring IC 23 and the sub unit 26 are thereafterturned OFF. Accordingly, the voltage monitor 20 is placed in a sleepmode. The sleep mode is a state in which although activation of themonitoring IC 23 and the sub unit 26 are terminated, activation of thestorage unit 27 is not terminated.

The monitoring IC 23 is connected to each detection port 20 d via thedetection wire δ. The plurality of detection ports 20 d are connected,via the detection lines 39, to both ends of the battery block 62 andbetween terminals of the plurality of unit batteries 63 constituting thebattery block 62. The monitoring IC 23 can detect voltage informationbetween the terminals of the unit batteries 63. The voltage informationmay be an actual voltage value, or may be, for example, informationconvertible to a voltage value, such as a current value flowing througha prescribed portion. The monitoring IC 23 can discharge the unitbatteries 63, as necessary. Therefore, a balancing treatment can beperformed in which the charging states of the unit batteries 63 areuniformized.

The sub unit 26 has a communication controller and an RF part. Themonitoring IC 23 and the sub unit 26 are communicably connected via thecommunication wire β. The sub unit 26 transmits, for example, a commandwirelessly received from the main unit 16, to the monitoring IC 23 viathe communication wire β. On the other hand, the monitoring IC 23transmits voltage information or the like to the sub unit 26 via thecommunication wire β. The storage unit 27 has a memory. The main unit 16and the sub units 26 constitute a wireless device.

Next, control of the battery monitoring apparatus 51 will be describedseparately at an initial operation and at a second operation or later.At an initial operation, the power switch 70 is turned ON for the firsttime to operate the battery monitoring apparatus 51, after the batterymonitoring apparatus 51 has been mounted on a vehicle. At a secondoperation or later, the power switch 70 is turned ON for the second timeor later to operate the battery monitoring apparatus 51, after thebattery monitoring apparatus 51 has been mounted on a vehicle.

FIG. 2 is a flowchart illustrating control of the battery monitoringapparatus 51 at an initial operation. Firstly, a processing flow inresponse to the power switch 70 being turned ON will be described. Inresponse to the power switch 70 being turned ON, the battery ECU 10 isactivated (S101), while the voltage monitors 20 are also activated(S102). Thereafter, the main unit 16 and the sub units 26 perform aconnection sequence (S103) to establish communication connection. Next,it is determined whether the main unit 16 and the sub units 26 haveestablished communication connection (S104). In response to determiningthat communication connection has not been established (S104: NO), theconnection sequence in S103 is performed again. On the other hand, inresponse to determining that communication connection has beenestablished (S104: YES), wireless communication is performed between themain unit 16 and the sub units 26 (S105).

Particularly, in the activation of the battery ECU 10 in S101, the powerswitches 13 a and 16 a are turned ON to activate the MCU 13 and the mainunit 16. In addition, in the activation of each voltage monitor 20 inS102, the power switches 23 a and 26 a are turned ON to activate themonitoring IC 23 and the sub unit 26.

In the connection sequence in S103, the main unit 16 and the sub units26 exchange information through wireless signals. Accordingly, the mainunit 16 and the sub units 26 establish information such as connectioninformation and voltage monitor information. The connection informationis information on identification numbers of the main unit 16 and the subunits 26, frequency channels used for wireless communication, datastructures of data to be communicated, and the like.

On the other hand, the voltage monitor information is information basedon the below-described number information, position information, andperiod information. Particularly, the voltage monitor information maycontain number information itself, position information itself, andperiod information itself, or may contain information such as calculatedvalues based thereon.

The number information is information indicating the number of voltagemonitors 20. The main unit 16 acquires number information, because, forexample, the number of sub units 26 to be sequentially communicated bythe main unit 16 may vary depending on the number of voltage monitors20. The sub units 26 acquire number information, because, for example,the interval at which the sub units 26 themselves communicate with themain unit 16 may vary depending on the number of voltage monitors 20.For acquiring the number information, for example, the sub units 26transmit their identification numbers to the main unit 16 throughwireless signals, and the main unit 16 counts the number of sub units 26from the number of received identification numbers. Furthermore, inorder that the sub units 26 can also acquire the number information, themain unit 16 wirelessly transmits the acquired number information to thesub units 26.

The position information is information indicating to which of thebattery blocks 62 each voltage monitor 20 is disposed. The main unit 16acquires position information, because, for example, which of thebattery blocks 62 corresponds to received voltage information to beprocessed may vary depending on the position of the voltage monitor 20.Each sub unit 26 acquires position information, because, for example,the address in the main unit 16 to which the sub unit 26 transmitsvoltage information may vary depending on the position of itscorresponding voltage monitor 20.

The position information can be acquired in the following manner. Forexample, each voltage monitor 20 detects a potential difference betweenthe potential of the battery block 62 corresponding to itself and theground potential, and wirelessly transmits the detected potentialdifference to the main unit 16, so that the main unit 16 can acquireposition information (order) of the voltage monitor 20 to which each subunit 26 belongs. The acquired position information is wirelesslytransmitted from the main unit 16 to the sub units 26, so that the subunits 26 can also acquire position information. In addition, forexample, an assembly worker or the like stores position information ineach voltage monitor 20 when assembling the voltage monitor 20, and thesub unit 26 wirelessly transmits the stored position information to themain unit 16 during the connection sequence, so that the sub unit 26 andthe main unit 16 can acquire position information. In addition, forexample, the voltage monitors 20 are sequentially activated in theascending order of the potentials of the corresponding battery blocks62, and the sub units 26 sequentially transmit their own identificationnumbers to the main unit 16 through wireless signals in the activatedorder of the voltage monitors 20, so that the main unit 16 can acquireposition information (order) of the voltage monitors 20 to which thecorresponding sub units 26 belong. In addition, the main unit 16wirelessly transmits the acquired position information to the sub units26, so that the sub units 26 can also acquire position information.

The period information is information indicating an acquisition periodof voltages of the unit batteries 63 by the voltage monitors 20. Themain unit 16 and the sub units 26 acquire period information, because,for example, the length of the period of communication between the mainunit 16 and the sub units 26 may vary depending on the acquisitionperiod of voltages. For example, when the acquisition period isintrinsic to each monitoring IC 23, each sub unit 26 acquires the ID ofthe monitoring IC 23 of the corresponding voltage monitor 20, andtransmits the acquired ID to the main unit 16 through wireless signals,so that the main unit 16 can acquire the period information of thevoltage monitor 20. In addition, the main unit 16 wirelessly transmitsthe period information to each sub unit 26, so that each sub unit 26 canalso acquire period information of other sub units 26.

In the connection sequence of S103, the main unit 16 and the sub units26 establish communication connection based on the acquired connectioninformation and voltage monitor information. In response to theestablishment of communication connection, the main unit 16 wirelesslytransmits a command by the MCU 13 to the sub units 26, and the sub units26 wirelessly transmit voltage information and the like to the main unit16, through the communication in S105.

Next, a processing flow in response to the power switch 70 being turnedOFF will be described. In response to the power switch 70 being turnedOFF (S151), the main unit 16 terminates wireless communication with thesub units 26 (S152). Thereafter, the main unit 16 stores connectioninformation and voltage monitor information in the storage unit 17(S153). Then, the battery ECU 10 is placed in a sleep mode (S154).

On the other hand, the sub units 26 terminate wireless communicationwith the main unit 16 (S152), thereafter perform a communicationtermination sequence (S155), and determine whether the communicationwith the main unit 16 has been terminated (S156). In response to failingto determine that the communication has been terminated (S156: NO), thecommunication termination sequence in S155 is repeated. On the otherhand, in response to determining that the communication has beenterminated (S156: YES), the sub units 26 store information such asconnection information and voltage monitor information in thecorresponding storage units 27 (S157). Thereafter, the voltage monitors20 are placed in a sleep mode (S158).

Particularly, in the communication termination of S152, the main unit 16terminates wireless communication of a command by the MCU 13 to the subunits 26. In the sleep of S154, the power switches 13 a and 16 a of theMCU 13 and the main unit 16 are turned OFF. In the communicationtermination sequence of S155, it is determined that the communicationhas been terminated, in response to the sub units 26 not receivingwireless signals from the main unit 16 for a prescribed time or longer.In the sleep of S158, the power switches 23 a and 26 a of the monitoringIC 23 and the sub units 26 are turned OFF.

FIG. 3 is a flowchart illustrating control of the battery monitoringapparatus 51 at a second operation or later. In response to the powerswitch 70 of a vehicle being turned ON, the battery ECU 10 is activated(S201), while the voltage monitors 20 are activated (S203). The mainunit 16 reads and refers to information stored in the storage unit 17 ofthe battery ECU 10 (S202), and each sub unit 26 reads and refers toinformation stored in the storage unit 27 of the corresponding voltagemonitor 20 (S204). Accordingly, the main unit 16 and the sub unit 26establish communication connection and start wireless communication(S205) without performing the connection sequence as performed at theinitial operation. Then, wireless communication is continued (S206).

The processing flow (S251 to S258) in response to the power switch 70being turned OFF is the same as at the initial operation (S151 to S158).Therefore, the main unit 16 and the sub units 26 come to updateconnection information and voltage monitor information stored in thestorage units 17 and 27, in response to the power switch 70 of a vehiclebeing turned OFF.

FIG. 4 is a flowchart illustrating control in response to disconnectionof communication connection while the power switch 70 is ON, that is,during communication. In response to occurrence of communicationinterruption (S302) while wireless communication is performed (S301),the main unit 16 performs interruption determination (S303). In responseto failing to determine that interruption has occurred (S303: NO), theinterruption determination (S303) is repeated. On the other hand, inresponse to determining that interruption has occurred in S303 (S303:YES), the main unit 16 reads and refers to information in the storageunit 17 (S304).

In addition, in response to occurrence of communication interruption(S302) while wireless communication is performed (S301), the sub units26 perform interruption determination (S305). In response to failing todetermine that interruption has occurred (S305: NO), the interruptiondetermination (S305) is repeated. On the other hand, in response todetermining that interruption has occurred in S305 (S305: YES), the subunits 26 read and refer to information in the corresponding storageunits 27 (S306).

Since the main unit 16 and the sub units 26 both read and refer toinformation in the corresponding storage units 17 and 27, the main unit16 and the sub units 26 establish communication re-connection andrestart wireless communication, without performing the connectionsequence as performed at the initial operation (S307).

Particularly, in the interruption determination of S303, the main unit16 determines that wireless communication has been interrupted, inresponse to not receiving wireless signals from the sub units 26 for aprescribed time or longer. In addition, in the interruptiondetermination of S305, the sub units 26 determine that wirelesscommunication has been interrupted, in response to not receivingwireless signals from the main unit 16 for a prescribed time or longer.

According to the present embodiment, the following effects are obtained.Since the main unit 16 and the sub units 26 perform communicationconnection using information stored in the storage units 17 and 27 at asecond operation or later, a time for acquiring connection informationand voltage monitor information can be saved. Therefore, communicationconnection at a second operation or later can be smoothly reestablished.

In addition, since the main unit 16 and the sub units 26 performcommunication connection using information stored in the storage units17 and 27 even when communication connection is disconnected duringcommunication, communication re-connection can be smoothlyreestablished.

Furthermore, since voltage monitor information stored in the storageunits 17 and 27 is based on three of the number information, theposition information, and the period information, acquisition of allthese three pieces of information can be omitted. This point alsofacilitates smooth reestablishment of communication connection. Thesmooth reestablishment of communication re-connection can also befacilitated when the main unit 16 and the sub units 26 both storeconnection information and voltage monitor information and use thestored information at a time of re-connection.

Moreover, power can be saved when the battery ECU 10 and the voltagemonitors 20 are placed in a sleep mode in response to the power switch70 being turned OFF. On the other hand, since the storage units 17 and27 are continuously activated even in a sleep mode, it is satisfactoryto have only a volatile memory, without the necessity of having anonvolatile memory. In addition, since the storage units 17 and 27 arecontinuously activated even in a sleep mode, communication re-connectioncan be smoothly reestablished without the necessity of activating thestorage units 17 and 27 at a second operation or later. Furthermore,since information in the storage units 17 and 27 is updated every timethe power switch 70 is turned OFF, information error, in whichinformation in the storage units 17 and 27 is not updated despiteconnection information and voltage monitor information actually havingbeen updated, can be prevented.

Second Embodiment

Next, a battery monitoring apparatus 52 according to a second embodimentwill be described. It is noted that in the following embodiments, amember or the like that is the same as or corresponds to that in theprevious embodiment is assigned with the same reference sign. However, abattery monitoring apparatus itself is assigned with a differentreference sign in each embodiment. For the present embodiment, pointsdifferent from the first embodiment will be primarily described.

FIG. 5 is a flowchart illustrating control of the battery monitoringapparatus 52 at a second operation or later. The present embodiment isdifferent from the first embodiment, in that immediately before sleeping(S254 and S258), the main unit 16 and the sub units 26 do not storeconnection information and voltage monitor information in the storageunits 17 and 27, that is, do not update connection information andvoltage monitor information in the storage units 17 and 27.

According to the present embodiment, the time and labor for updatinginformation stored in the storage units 17 and 27 can be saved at theend of a second operation or later, although there is the risk ofinformation error.

Third Embodiment

FIG. 6 is a circuit diagram illustrating a battery monitoring apparatus53 according to a third embodiment. For the present embodiment, pointsdifferent from the first embodiment will be primarily described. Themain unit 16 is not provided with the power switch 16 a, and power isalways supplied to the main unit 16. Therefore, the battery ECU 10 isconfigured such that in response to the power switch 70 being turnedOFF, only the power switch 13 a of the MCU 13 is turned OFF, and themain unit 16 and the storage unit 17 are continuously activated.

In addition, each sub unit 26 is not provided with the power switch 26a, and power is always supplied to each sub unit 26. Therefore, eachvoltage monitor 20 is configured such that in response to the powerswitch 70 being turned OFF, only the power switch 23 a of the monitoringIC 23 is turned OFF, and the sub unit 26 and the storage unit 27 arecontinuously activated.

FIG. 7 is a flowchart illustrating control of the battery monitoringapparatus 53 at an initial operation. After the main unit 16 storesinformation in the storage unit 17 (S153), the battery ECU 10 is notplaced in a sleep mode and terminates only the activation of the MCU 13(S154 c). In addition, after each sub unit 26 stores information in thecorresponding storage unit 27 (S157), the voltage monitor 20 is notplaced in a sleep mode and terminates only the activation of themonitoring IC 23 (S158 c). After storing information, the main unit 16and each sub unit 26 perform communication for every prescribed periodto maintain communication connection.

FIG. 8 is a flowchart illustrating control of the battery monitoringapparatus 53 at a second operation or later. In response to the powerswitch 70 being turned ON, the battery ECU 10 is activated (S201), whilethe voltage monitors 20 are activated (S203). Then, the main unit 16 andthe sub units 26 start wireless communication through the maintainedcommunication connection, without performing the connection sequence asperformed at the initial operation (S205). Then, wireless communicationis maintained (S206).

The processing flow (S251 to S253, S254 c, S255 to S257, and S258 c) inresponse to the power switch 70 being turned OFF is the same as at theinitial operation (S151 to S153, S154 c, S155 to S157, and S158 c).

According to the present embodiment, wireless communication is performedby the maintained communication connection, which enables wirelesscommunication to be more smoothly restarted.

In addition, in the present embodiment, communication is performed forevery prescribed period while maintaining communication connection,after communication is terminated in S152 and S156 at the initialoperation illustrated in FIG. 7 and after communication is terminated inS252 and S256 at the second operation or later illustrated in FIG. 8, asdescribed above. Therefore, in other words, as illustrated in FIG. 9,the wireless device performs wireless communication between the mainunit 16 and the sub units 26 in a prescribed first communication mode M1while the power switch 70 is ON, and in a second communication mode M2,whose power consumption is smaller than the first communication mode M1,while the power switch 70 is OFF. Therefore, while the power switch 70is OFF, communication connection can be maintained with reduced powerconsumption by the second communication mode M2.

More specifically, the sub units 26 wirelessly communicate with the mainunit 16 for a prescribed first communication period T1 in the firstcommunication mode M1, and the sub units 26 wirelessly communicate withthe main unit 16 for a second communication period T2, which is longerthan the first communication period T1, in the second communication modeM2. Therefore, in the second communication mode M2, the communicationperiod is longer, which enables the reduction of power consumption andthe maintenance of communication connection to be efficiently balanced.

In addition, in the present embodiment, wireless communication ismaintained by the second communication mode M2 even while the powerswitch 70 is OFF, with the result that the timer of the main unit 16 andthe timers of the sub units 26 are synchronized even while the powerswitch 70 is OFF. The timers are configured such that in wirelesscommunication, the main unit 16 and each sub unit 26 synchronize thetransmission timing of themselves and the reception timing of the otherfollowed by synchronizing the transmission timing of the other and thereception timing of themselves. Therefore, in response to the powerswitch 70 being turned from OFF to ON, wireless communication by thefirst communication mode M1 can be smoothly restarted using alreadysynchronized timers, without synchronizing the timers between the mainunit 16 and the sub units 26 again.

Fourth Embodiment

Next, a battery monitoring apparatus 54 according to a fourth embodimentwill be described. For the fourth embodiment, points different from thethird embodiment will be primarily described.

FIG. 10 is a flowchart illustrating control of the battery monitoringapparatus 54 at a second operation or later. The present embodiment isdifferent from the third embodiment, in that after terminatingcommunication with the sub units 26 (S252), the main unit 16 does notstore connection information and voltage monitor information in thestorage unit 17, that is, does not update connection information andvoltage monitor information in the storage unit 17. In addition, thepresent embodiment is different from the third embodiment, in that afterterminating communication with the main unit 16 (S256), the sub units 26do not store connection information and voltage monitor information inthe corresponding storage units 27, that is, do not update connectioninformation and voltage monitor information in the corresponding storageunits 27.

According to the present embodiment, the time for updating informationstored in the storage units 17 and 27 can be saved at the end of asecond operation or later, although there is a risk of informationerror.

Fifth Embodiment

Next, a battery monitoring apparatus 55 according to a fifth embodimentwill be described. For the present embodiment, points different from thethird embodiment will be primarily described.

FIG. 11 is a flowchart illustrating control of the battery monitoringapparatus 53 at an initial operation. In response to the power switch 70being turned ON, the battery ECU 10 is activated (S101), while thevoltage monitors 20 are also activated (S102). Thereafter, the main unit16 and the sub units 26 perform a connection sequence (S103) toestablish communication connection. At this time, the main unit 16 andthe sub units 26 synchronize their timers. Next, it is determinedwhether the main unit 16 and the sub units 26 have establishedcommunication connection (S104). In response to determining thatcommunication connection has not been established (S104: NO), theconnection sequence in S103 is performed again. On the other hand, inresponse to determining that communication connection has beenestablished (S104: YES), wireless communication by the firstcommunication mode M1 is performed between the main unit 16 and the subunits 26 (S105).

Thereafter, in response to the power switch 70 being turned OFF (S151),an elapsed time therefrom is measured by the main unit 16 with its owntimer. In response to the elapsed time reaching a prescribed time, thatis, after a prescribed time has elapsed since the power switch 70 wasturned OFF, the main unit 16 transmits a second switching signal toinstruct the sub units 26 to switch to the second communication mode M2,through the current wireless communication by the first communicationmode M1 (S151 e), while switching its own state from the state for thefirst communication mode M1 to the state for the second communicationmode M2 (S152 e). Thereafter, the battery ECU 10 stores connectioninformation and voltage monitor information in the storage unit 17(S153).

On the other hand, each sub unit 26 determines whether it has receivedthe second switching signal (S155 e). In response to failing todetermine that the second switching signal has been received (S155 e:NO), the determination in S155 e is repeated. On the other hand, inresponse to determining that the second switching signal has beenreceived in S155 e (S155 e: YES), the sub unit 26 switches its own statefrom the state for the first communication mode M1 to the state for thesecond communication mode M2 (S156 e). Accordingly, the communicationmode between the main unit 16 and the sub unit 26 switches from thefirst communication mode M1 to the second communication mode M2.Thereafter, each voltage monitor 20 stores information such asconnection information and voltage monitor information in thecorresponding storage unit 27 (S157), while terminating the activationof the monitoring IC 23 (S158 c).

Thereafter, the main unit 16 and the sub unit 26 maintain communicationconnection through the wireless communication by the secondcommunication mode M2. In the second communication mode M2, the timersof the main unit 16 and the sub unit 26 are continuously synchronized byexchanging timer information between the main unit 16 and the sub unit26. In addition, at a prescribed time, the sub unit 26 transmits voltageinformation of the unit batteries 63 to the main unit 16.

FIG. 12 is a flowchart illustrating control of the battery monitoringapparatus 53 at a second operation or later. In response to the powerswitch 70 being turned ON, the battery ECU 10 is activated (S201), whilethe voltage monitors 20 are activated (S203). The main unit 16 readsinformation stored in the storage unit 17 of the battery ECU 10 (S202),and each sub unit 26 reads information stored in the storage unit 27 ofthe corresponding voltage monitor 20 (S204). Then, the main unit 16 andthe sub unit 26 switch from the second communication mode M2 to thefirst communication mode M1 (S205) using the read information and themaintained communication connection by the second communication mode M2,without performing the connection sequence and the timer synchronizationas performed at the initial operation.

Specifically, in S205, the main unit 16 transmits a first switchingsignal to instruct the sub units 26 to switch to the first communicationmode M1 through the current wireless communication by the secondcommunication mode M2. Then, the main unit 16 switches its own statefrom the state for the second communication mode M2 to the state for thefirst communication mode M1. At this time, the main unit 16 refers toinformation read from the storage unit 17. On the other hand, inresponse to receiving the first switching signal, each sub unit 26switches its own state from the state for the second communication modeM2 to the state for the first communication mode M1. At this time, thesub unit 26 refers to information read from the storage unit 27. In thismanner, the communication mode between the main unit 16 and each subunit 26 switch from the second communication mode M2 to the firstcommunication mode M1 (S205). Then, the main unit 16 and each sub unit26 wirelessly communicate by the first communication mode M1 (S206).

The subsequent control (S251, S251 e, S252 e, S253, S255 e, S256 e,S257, and S258 c) in response to the power switch 70 being turned OFF isthe same as at the initial operation (S151, S151 e, S152 e, S153, S155e, S156 e, S157, and S158 c).

According to the present embodiment, the following effects are obtained.For switching from the second communication mode M2 to the firstcommunication mode M1, the main unit 16 and each sub unit 26 use thecorresponding voltage monitor information stored in the storage units 17and 27 to establish the switching. Therefore, even when voltage monitorinformation is required for the switching, the switching can be smoothlyreestablished.

In addition, in the second communication mode M2, each sub unit 26transmits voltage information of the unit batteries 63 to the main unit16 at times. Therefore, if the voltage information changes while thepower switch 70 is OFF, the battery ECU 10 can start processing withupdated voltage information in response to the power switch 70 beingturned ON.

In addition, in response to a prescribed time having elapsed after thepower switch 70 was turned OFF, the first communication mode M1 isswitched to the second communication mode M2. Therefore, the switchingcan be simply and timely performed. In addition, the prescribed time ismeasured by the timers. Therefore, switching from the firstcommunication mode M1 to the second communication mode M2 can be simplyand timely performed using the timers.

In addition, the second switching signal is transmitted through thecommunication by the first communication mode M1 thereby to switch tothe second communication mode M2, whereas the first switching signal istransmitted through the communication by the second communication modeM2 thereby to switch to the first communication mode M1. Therefore, thecurrent communication modes M1 and M2 can be used to simply switch tothe other communication modes M2 and M1.

Sixth Embodiment

Next, a battery monitoring apparatus 56 according to a sixth embodimentwill be described. For the present embodiment, points different from thefifth embodiment will be primarily described. The first communicationmode M1 is the same as in the fifth embodiment. Therefore, in the firstcommunication mode M1, separate communication is performed in which themain unit 16 separately transmits signals to the sub units 26.

FIG. 13 is a schematic diagram illustrating a second communication modeM2 according to the present embodiment. In the second communication modeM2, broadcast communication is performed in which the main unit 16transmits one broadcast signal to the plurality of sub units 26. Thebroadcast signal contains a prescribed handling signal and theabove-described first switching signal. The handling signal is a signalto be transmitted for prescribed periods while the power switch 70 isOFF, and contains information for synchronizing timers between the mainunit 16 and the sub units 26. As described above, the first switchingsignal is transmitted in response to the power switch 70 switching fromOFF to ON. The main unit 16 may transmit the broadcast signal,immediately at, for example, the switching of the communication mode, oraccording to a schedule previously set between the main unit 16 and thesub units 26.

The sub units 26, for example, check synchronization between the timers,by sequentially returning signals to the main unit 16 at different timesafter reception of the handling signal. Furthermore, at a prescribedtiming, each sub unit 26 returns voltage information of the unitbatteries 63 to the main unit 16, after reception of the handlingsignal. It is noted that although each broadcast signal preferably has ashort output time from the viewpoint of consumption power and immediatestate transition, it may be continuously output for a certain time orfor certain periods, so that all the sub units 26 can reliably receivethe broadcast signal.

According to the present embodiment, in the second communication modeM2, broadcast communication is performed in which the main unit 16transmits one broadcast signal to the plurality of sub units 26.Therefore, the reduction of power consumption and the maintenance ofcommunication connection can be efficiently balanced. In addition, thesub units 26 sequentially return signals to the main unit 16 atdifferent times after reception of the handling signal in the broadcastsignal. Therefore, interference between signals can be preventedcompared to when signals are returned simultaneously. Furthermore, suchprevention of the interference between signals can reduce power withwhich the sub units 26 return signals.

OTHER EMBODIMENTS

The above-described embodiments can be modified and carried out in thefollowing manner. For example, the voltage monitor information stored inthe storage units 17 and 27 may be based on only one or two of theabove-described number information, position information, and periodinformation. Specifically, the voltage monitor information may be basedon at least the number information. In addition, the voltage monitorinformation may be based on at least the position information. Inaddition, the voltage monitor information may be based on at least theperiod information. In addition, the voltage monitor information may bebased on at least the number information and the position information.In addition, the voltage monitor information may be based on at leastthe number information and the period information. In addition, thevoltage monitor information may be based on at least the positioninformation and the period information.

The storage unit 17 or 27 may be disposed to at least one of the batteryECU 10 and each voltage monitor 20 and not disposed to the other.Specifically, for example, the storage unit 17 may be disposed to onlythe battery ECU 10, and the storage unit 27 may not be disposed to eachvoltage monitor 20. Then, the sub units 26 may wirelessly receiveconnection information and voltage monitor information from the mainunit 16. In addition, for example, in a case in which the storage unit17 is disposed only to the battery ECU 10, each sub unit 26 may notwirelessly receive connection information and voltage monitorinformation from the main unit 16. In this case, connection processingwith each sub unit 26 performed in the main unit 16 can also be omitted.

In addition, for example, only one of the voltage monitors 20 mayinclude the storage unit 27, and the battery ECU 10 and the others ofthe voltage monitors 20 may not include the storage unit 17 or 27. Then,the main unit 16 and the others of the sub units 26 may wirelesslyreceive connection information and voltage monitor information from thesub unit 26 in the voltage monitor 20 including the storage unit.

In addition, for example, instead of being activated in response toactivation of the power switch 70, the battery ECU 10 and the voltagemonitors 20 may start activation in response to previous reception ofsignals or the like. In addition, for example, the storage units 17 and27 may be mounted with a nonvolatile memory so as to terminateactivation in response to the power switch 70 being turned OFF.

In addition, for example, in the third to sixth embodiments, the storageunits 17 and 27 may not be included. Even in this case, at a secondoperation or later, wireless communication can be smoothly restarted byperforming wireless communication through the maintained communicationconnection. That is, wireless communication in the first communicationmode M1 can be smoothly restarted by the maintained communicationconnection in the second communication mode M2.

In addition, for example, in the fifth and sixth embodiments, thebattery ECU 10 may terminate activation of the MCU 13, in response tothe power switch 70 being turned OFF, that is, after S153 in FIG. 11. Inaddition, for example, in the fifth and sixth embodiments, each sub unit26 may not transmit voltage information of the unit batteries 63 to themain unit 16 in the second communication mode M2. In addition, forexample, in the fifth and sixth embodiments, only the main unit 16 mayunilaterally transmit signals to the sub units 26, and the sub units 26may not return signals to the main unit 16, in the second communicationmode M2. In addition, for example, in the sixth embodiment, the subunits 26 may simultaneously return signals to the main unit 16.

Although the present disclosure has been described in accordance withexamples, it is understood that the present disclosure is not limited tothe examples and structures. The present disclosure also encompassesvarious variation examples or variations within the equivalent scope. Inaddition, various combinations and forms, and furthermore, othercombinations and forms which include only one component, more than that,or less than that, to the various combinations and forms also fallwithin the category or conceptual scope of the present disclosure.

What is claimed is:
 1. An apparatus configured to monitor a plurality ofunit batteries provided to a battery pack mounted on a vehicle,comprising: a battery ECU; voltage monitors disposed to correspondingbattery blocks into which a plurality of the unit batteries is grouped,to detect voltage information of the unit batteries; and a wirelessdevice, wherein in a battery monitoring apparatus in which the wirelessdevice includes a main unit disposed to the battery ECU and sub unitsdisposed to the corresponding voltage monitors, and the main unitwirelessly transmits a command by the battery ECU to the sub units, andthe sub units wirelessly transmit the voltage information to the mainunit, in response to establishment of communication connection ofwireless communication between the main unit and the sub units, the mainunit receives wireless signals from the sub units prior to initialestablishment of the communication connection, such that the wirelessdevice acquires voltage monitor information, which is information of thevoltage monitors, and establishes the communication connection using thevoltage monitor information, at least one of the battery ECU and eachvoltage monitor is disposed with a storage unit configured to store thevoltage monitor information, and at a time of re-connection in whichcommunication re-connection is reestablished after disconnection of theinitial communication connection, the wireless device establishes thecommunication re-connection using the voltage monitor information storedin the storage unit.
 2. The battery monitoring apparatus according toclaim 1, wherein the re-connection comprises performing thecommunication re-connection after the disconnection of the communicationconnection, while a power switch, which is an activation switch of apower unit for running the vehicle, is ON.
 3. The battery monitoringapparatus according to claim 1, wherein the battery ECU and the voltagemonitors are each provided with the storage unit, and the main unit andthe sub units are each configured to store the voltage monitorinformation in the storage unit disposed together with itself to thebattery ECU or the voltage monitor, and use the stored voltage monitorinformation at the re-connection.
 4. The battery monitoring apparatusaccording to claim 1, wherein the wireless device updates the voltagemonitor information stored in the storage unit in response to a powerswitch, which is an activation switch of a power unit for running thevehicle, being turned OFF.
 5. The battery monitoring apparatus accordingto claim 1, wherein the wireless device disconnects the communicationconnection in response to a power switch, which is an activation switchof a power unit for running the vehicle, being turned OFF, and there-connection includes performing the communication re-connection afterthe communication connection has been disconnected in response to thepower unit being turned OFF.
 6. The battery monitoring apparatusaccording to claim 1, wherein the wireless device terminates activation,but the storage unit is placed in a sleep mode in which activation isnot terminated, in response to a power switch, which is an activationswitch of a power unit for running the vehicle, being turned OFF.
 7. Thebattery monitoring apparatus according to claim 1, wherein the wirelessdevice performs the wireless communication while a power switch, whichis an activation switch of a power unit for running the vehicle, is ON,and maintains the communication connection, even when the power switchis turned OFF, to perform the wireless communication by the maintainedcommunication connection in response to the power switch thereafterbeing turned ON.
 8. An apparatus configured to monitor a plurality ofunit batteries provided to a battery pack mounted on a vehicle,comprising: a battery ECU; voltage monitors disposed to correspondingbattery blocks into which a plurality of the unit batteries are grouped,to detect voltage information of the unit batteries; and a wirelessdevice, wherein in a battery monitoring apparatus in which the wirelessdevice includes a main unit disposed to the battery ECU and sub unitsdisposed to the corresponding voltage monitors, and the main unitwirelessly transmits a command by the battery ECU to the sub units, andthe sub units wirelessly transmit the voltage information to the mainunit, in response to establishment of communication connection ofwireless communication between the main unit and the sub units, the mainunit receives wireless signals from the sub units prior to establishmentof the communication connection, such that the wireless device acquiresvoltage monitor information, which is information of the voltagemonitors, and establishes the communication connection using the voltagemonitor information, and the wireless device performs the wirelesscommunication while a power switch, which is an activation switch of apower unit for running the vehicle, is ON, and maintains thecommunication connection, even when the power switch is turned OFF, toperform the wireless communication by the maintained communicationconnection in response to the power switch thereafter being turned ON.9. The battery monitoring apparatus according to claim 8, wherein thewireless device performs wireless communication in a prescribed firstcommunication mode while the power switch is ON, and performs wirelesscommunication in a second communication mode, whose power consumption issmaller than the first communication mode, while the power switch isOFF.
 10. The battery monitoring apparatus according to claim 9, whereinat least one of the battery ECU and a plurality of voltage monitors isdisposed with a storage unit configured to store the voltage monitorinformation, and in performing switching from the second communicationmode to the first communication mode, the wireless device establishesthe switching using the voltage monitor information stored in thestorage unit.
 11. The battery monitoring apparatus according to claim 9,wherein the sub units perform wireless communication with the main unitfor a prescribed first communication period in the first communicationmode, and the sub units perform wireless communication with the mainunit for a second communication period, which is longer than the firstcommunication period, in the second communication mode.
 12. The batterymonitoring apparatus according to claim 9, wherein in the firstcommunication mode, separate communication is performed in which themain unit separately transmits signals to the sub units, and in thesecond communication mode, broadcast communication is performed in whichthe main unit transmits each broadcast signal to a plurality of the subunits.
 13. The battery monitoring apparatus according to claim 12,wherein a plurality of the sub units sequentially returns signals to themain unit at different times after reception of the broadcast signal.14. The battery monitoring apparatus according to claim 9, wherein thesub units transmit the voltage information to the main unit in thesecond communication mode.
 15. The battery monitoring apparatusaccording to claim 9, wherein the first communication mode is switchedto the second communication mode, in response to a prescribed timehaving elapsed after the power switch was turned OFF.
 16. The batterymonitoring apparatus according to claim 15, wherein the main unit andthe sub units have corresponding prescribed timers, and synchronize,based on the timers, a transmission timing of one of the main unit andeach sub unit and a reception timing of the other main unit and each subunit, and the prescribed time is measured by the timers.
 17. The batterymonitoring apparatus according to claim 9, wherein the main unit and thesub units have corresponding prescribed timers, and synchronize, basedon the timers, a transmission timing of one of the main unit and eachsub unit and a reception timing of the other main unit and each subunit, and the timers are synchronized by exchanging information on thetimers between the main unit and each sub unit, in the secondcommunication mode.
 18. The battery monitoring apparatus according toclaim 9, wherein in response to the power switch being turned from OFFto ON, the main unit transmits a prescribed first switching signal tothe sub units through wireless communication by the second communicationmode, so that the second communication mode is switched to the firstcommunication mode, and in response to the power switch being turnedfrom ON to OFF, the main unit transmits a prescribed second switchingsignal to the sub units through wireless communication by the firstcommunication mode, so that the first communication mode is switched tothe second communication mode.
 19. The battery monitoring apparatusaccording to claim 1, wherein the voltage monitor information isinformation based on at least one of number information indicating thenumber of the voltage monitors, position information indicating to whichof the battery blocks each voltage monitor is disposed, and periodinformation indicating an acquisition period of voltages of the unitbatteries by the voltage monitors.
 20. The battery monitoring apparatusaccording to claim 19, wherein the voltage monitor information isinformation based on all the three of the number information, theposition information, and the period information.